when quickly switch among songs, calling -stop, it may exit -startInternal before calling -failWithErrorCode(in a thread, for example parse bytes thread), however, before exiting -startInternal, state is set as AS_INITIALIZED, but in -failWithError, state is set as AS_STOPPED, so the -stop is in a dead loop.
so before set as AS_STOPPED in failWithError, it should check wheather the state is AS_INITIALIZED.
when quickly switch among songs, calling -stop, it may exit -startInternal before calling -failWithErrorCode(in a thread, for example parse bytes thread), however, before exiting -startInternal, state is set as AS_INITIALIZED, but in -failWithError, state is set as AS_STOPPED, so the -stop is in a dead loop.
so before set as AS_STOPPED in failWithError, it should check wheather the state is AS_INITIALIZED.